An attachment system is know from German Offenlegungsschrift 30 37 938. This system relates to a prefabricated structural element for liquid surface heating, and has a double layer construction comprising a flexible strip of foil. Strips of foam material are fastened to the strip of foil and lie transverse to the longitudinal axis of the strip of foil and parallel to one another. The width and spacing of the foam strips is determined so that the structural element can be rolled into a bundle.
This structural element is of relatively light structure and can be transported in a small space when rolled into a ball. Because of its construction, the structural element is approximately 20 to 35 mm in thickness and is subject to no bending stresses whatsoever.
Attachable/detachable elements which can be used for the attachment system according to the present invention are disclosed in German Offenlegungsschrift 23 45 843. This document also discloses a base plate in the form of a carrier having sheathing extending lengthwise to receive the pedestal of an element for attaching and detaching the element from it. This known carrier is not provided for and is not suitable for resistance to bending stresses. The danger of shearing exists both in the sheathing and in the pedestal to and from which it can be attached and detached.